If you’ve ever been emailed an attachment, but lacked the application required to open it, you’ve probably spent some time scrabbling around online looking for a free viewer or open source app that can open the file. Alternatively, upload the file to Zamzar and you can get it converted to one of a range of other file formats and then download it again – without paying a penny.

If you're a genuine YouTube addict, you'll be glad to hear that you can keep up with the latest viral videos on a 3G smartphone or PDA with YouTube Mobile. So, you can fritter away yet more valuable time on your way to work, or even on your lunch break. There aren’t anywhere near as many videos as on the full website, but there’s plenty to look at.

We had more than a little trouble getting it to work with our Windows Mobile smartphones, but theoretically, any 3G device capable of using the RTSP protocol should work fine. A word of warning though, unless you’ve got an unlimited 3G data tariff, we’d give it a miss. Otherwise you could rack up a painfully hefty data bill in no time at all.

If you’re too lazy to voluntarily learn a few useful keypresses, then Keyboard Jedi forces you to. Enable Keyboard Jedi while using any program and it kidnaps your mouse cursor and confines it within its boundary box. Every keyboard shortcut you use is then listed in Keyboard Jedi’s window. You can even annotate the logged keypresses and paste the results to a text file so you can share your quick-fingered knowledge with friends and family.

If you were wondering how you could make using Google any simpler, well you could make its search engines and groups easier to access from smartphones or mobile devices with low resolution screens. And that’s exactly what Simply Google does; it compiles all the Google searches and a few more besides, and collects them into a simple list, which is easily navigable even on the most compact web-enabled devices.

Parking in central London isn’t much fun, but Park-Up aims to make the process significantly less painful. It has an extensive database of parking spaces both inside and around the Congestion Charge zone. Simply search by street name or postcode and you’ll be presented with a map of the local parking spaces as well as their operating times and prices. And best of all, the site’s been designed with mobile browsers in mind.

If your job takes you all over the world and you want to make the most of our spare time, then Gridskipper is a great resource for finding the best hotels, restaurants and night life, wherever you are. It even claims to pinpoint “the hottest local debauchery”, if that’s your bag. Those with less exotic tastes will be happy with the useful maps, which pinpoint local cafés, restaurants and attractions.